We propose to continue purification of E. coli replication proteins responsible for the conversion of 0X174 viral DNA to its replicative form (RF), the multiplication of these RF and, finally, the synthesis of viral strands. These proteins include: dnaB, dnaC, dnaG, proteins i, n and u, rep, and cisA. We intend to study the structures and functions of these proteins and to separate and examine the multiple steps which make up each of the replicative stages in the 0X174 cycle. We also plan to search for ways in which we may examine factors which control and regulate these proteins and steps in the replicative pathways. BIBLIOGRAPHIC REFERENCES: Zechel, K., Bouche, J-P. and Kornberg, A. Replication of Phage G4: A Novel and Simple System for the Initiation of DNA Synthesis. J. Biol. Chem. 250, 4684 (1975). Weiner, J.H., McMacken, R. and Kornberg, A. Isolation of an Intermediate which Precedes dnaG RNA Polymerase Patricipation in Enzymatic Replication of Bacteriophage Phi X174 DNA. Proc. Nat. Acad. Sci. 73, 752 (1976).